Apparatus for preparing foundry molds or cores from cold quick setting sand/binder/catalyst mixtures

ABSTRACT

A method and apparatus for preparing foundry moulds or cores wherein separate charges of sand and binder on the one hand and sand and catalyst on the other hand are supplied to a mixing chamber in which the separate charges are mechanically intermixed to produce a final sand/binder/catalyst mixture. The final mixture is then passed by gravity into a blowing chamber and the mixing chamber and the blowing chamber are moved apart to allow the final mixture to be blown from the blowing chamber into a mould or core box and further to allow the mixing chamber to be cleaned by suitable cleaning means.

United States Patent [191 Edwards [451 July 9, 1974 [54] APPARATUS FORPREPARING FOUNDRY 3,439,733 4/1969 Miller et a1. 164/21 X MOLDS 0 CORESFROM COLD QUICK 3,494,412 2/1970 Abraham 259/8 X 3,580,326 5/1971Edwards 164/21 UX if? g BINDER/ CATALYST 3,662,812 5/1972 Godding 164/21x [75] Inventor: Albert Edwards, Peterborough, FOREIGN PATENTS ORAPPLICATIONS England 784,525 10/1957 Great Britain 259/8 [73] Assignee:Baker Perkins Limited,

Pet rsb r h, E l d Primary Exammer--R. Spencer'Annear [2 F ed Mar 4 1972Attorney, Agent, or Firm-Larson, Taylor and Hinds 21 A l. N 237,699 1 pp57 ABSTRACT 30 Foreign Application p i D A method and apparatus forpreparing foundry Mar 29 1971 Great Britain 8094/7] moulds or coreswherein separate charges of sand and 197] Great Britain 41 m binder onthe one hand and sand and catalyst on the v other hand are supplied to amixing chamber in which the separate charges are mechanically intermixedto 2] US. Cl 164/158, 164/22, 1642/28/08, produce a fin a1sandlbinder/catalyst mixture. The final [51] Int Cl B22C 15/22 mixtureis then passed by gravity into ablowing cham- [58] Fieid T l64/2O 22 herand the mixing chamber and the blowing chamber 259/7 8 are moved apartto allow the final mixture to be blown from the blowing chamber into amould or core box 56] References Cited and further to allow the mixingchamber to be cleaned UNITED STATES PATENTS by suitable cleaning means.

2,223,018 11/1940 Christensen 259/7 12 Claims, 7 Drawing FiguresPATENTED JUL 91974 SHEET PATENTEU JUL 91974 SHEET 3 BF 3 FlGb.

APPARATUS FOR PREPARING FOUNDRY MOLDS OR CORES FROM COLD QUICK SETTINGSAND/BINDER/CATALYST MIXTURES This invention relates to a method andapparatus for preparing foundry moulds or cores from a quick coldsetting sand/binder/catalyst mixture.

The invention provides a method of preparing a foundry mould or corecomprising supplying separate charges of sand and binder on the one handand sand and catalyst on the other hand to a mixing chamber in which theseparate charges are mechanically intermixed to produce a finalsand/binder/catalyst mixture, passing the final mixture by gravity intoa blowing chamber and moving the mixing chamber and the blowing chamberapart to allow the final mixture to be blown from the blowing chamberinto a mould or core box and to allow the mixing. chamber to be cleanedby cleaning means.

.Preferably, metered quantities of said charges are supplied to themixing chamber whilst an outlet of the mixing chamber is closed, saidcharges being mixed in the mixing chamber for a predetermined timeperiod and the outlet then being opened to discharge the final mixture.

The invention may be carried into effect either by movement of themixing chamber to a position in which it is cleaned by said cleaningmeans, or alternatively by movement of the blowing chamber to a positionin which the final mixture is blown from the blowing chamber into themould or core box. The invention further provides apparatus forpreparing foundry moulds or cores comprising a mixing chamber, supplymeans for providing the mixing chamber with separate charges of sand andbinder on the one hand and sand and catalyst on the other hand, amechanical mixing element in the mixing chamber, an outlet from themixing. chamber for passing material by gravity from the mixing chamberinto a blowing chamber, means for moving the mixing chamber and theblowing chamber apart to allow the final mixture to be discharged fromthe blowing chamber into a mould or core box and to allow the mixingchamber to be cleane'dby cleaning means..-

y The mixing chamber may be movable between a first position in which itis adapted to deliver the mixed material to the blowing chamber, and asecond position in which the mixing chamber is adapted to be cleaned bysaid cleaning means, or alternatively the blowing chamber may be movablebetween a first position in which it is adapted to receive the finalmixture from the mixingchamber, and a second position in which the finalmixture can be discharged into the mould or core box. Preferably, thepurging means comprises compressed gas.

The invention will now be described, by way of example, with referenceto the accompanying drawings in which:

FIG. 1 is a diagrammatic view of apparatus according to one embodimentof the invention, and

FIGS.- 2 and 3 are diagrammatic view of modified FIG. 6 is a verticalsection of a cylindrical mixing chamber showing the mixer.

FIG. 7 is a top view of FIG. 6.

In the arrangement shown in FIG. 1, a pair of screwtype combined mixerconveyor units 1, for example units of the type described in our US.Patent Specification No. 1,051,651 are supplied with metered quanti tiesof sand and resin (or any other binder) and'sand and catalystrespectively and discharge their respective mixtures into twinreservoirs 2. When material is required to prepare a mould or core, afirst slide valve 3 controlling communication between the reservoirs anda mixing chamber 4 is opened admitting the separate mixtures to themixing chamber.

The mixing chamber may be of the type disclosed in our co-pending PatentApplication No. 8095/71 which has been cognated'with our other'co-pending Application No. 55725/71, i.e., of the type shownin FIGS. 6and 7 comprising a vertical cylindrical wall 8, a base wall with anoutlet 10 therein and a vertical=axis rotary mixing element 12 in thechamber, the element comtached thereto, or diametrically opposed springsteel blades adapted to sweep the base wall and a further pair of springsteel blades 18 angularly offset from the first pair adapted to sweepthe vertical wall. The second pair of blades 18 are fixedly attached toa cross member 20 which also serves to sweep the roof of the mixingchamber. With this construction, if 'a mixing element, havingdiametrically opposed spring steel blades, is rotated at about RPM, ithas been found that the materials can be intermixed as they fall throughthe mixing chamber in about three quarters of a revolution of the mixingelement. Accordingly, the outlet from the mixing chamber, controlled bya second slide valve 5 is suitably angularly offset from the inlet. Aconventional blowing chamber or core shooter 6 has an inlet 6acontrolled by a third slide valve 7, the inlet 6av being formed in a topplate 6b. j

Preferably, a rotary mixing element having said pair of tangentiallymounted angle iron members with ri gid blades attached thereto,comprising the first pair of blades, is used, the mixing chamber beingused as a batch mixer wherein metered amounts of the two separate mixersare introduced into the mixing chamber and intermixed for apredetermined period of time and then discharged.

During mixing, valve 7 can be open and valve 5 is closed. Whensufficient material for a core or mould being prepared has beendelivered to the mixing chamber, valve 3 is closed, and after mixing,the mixing chamber is slid across the top plate 6b, valve 5 is openedand when the mixing chamber outlet communicates with inlet 6a (as showndotted) the final mixture is transferred by gravity into the coreshooter. The core mixing chamber is connected to a source of com pressedair which enters the chamber through tangentially disposed ports in thecylindrical wall to purge any materialremaining in the chamber into asuitable receptacle.

After purging, valve is again closed, valve 7 is opened and theapparatus is ready for the preparation of a further mould or core.

The apparatus shown in FIG. 2 is similar to that shown in FIG. 1 andlike references are used to refer to like parts. The reservoirs 2 andvalve 3 are eliminated and the separate mixtures are supplied to themixing chamber by operation of the combined mixer conveyor units 1 for aperiod sufficient to provide the required amount of materials for a coreor mould being prepared. In this case, after mixing, the final mixtureis transferred directly by gravity into the core shooter by openingvalves 5 and 7. Then these valves are closed, the mixture is shot, andthe mixing chamber is moved to one side (shown dotted) for purging byopening of valve 5. After purging the mixing chamber is returned to itsinitial position for the next cycle.

The apparatus shown in FIG. 3 is similar in construction and operationto the apparatus shown in FIG. 2 except that the outlet slide valve 5 ofthe mixing chamber is eliminated and the materials received from units 1are intermixed by the rotary mixing element as they are passedsubstantially straight through the mixing chamber and into the coreshooter.

FIG. 4 shows apparatus according to another embodiment of the inventionin a mixing and charging position and FIG. 5 shows the apparatus in aposition in which the core shooter or blowing chamber has been moved toa position for blowing the core or mould and for cleaning the mixingchamber.

In operation, separate mixtures of sand and binder on the one hand andsand and catalyst on the other hand are supplied from twin mixerconveyor type units 1 through a divided hopper 2 into a mixing chamber4. Mechanical mixing means of the type as described above is operativein the mixing chamber, the duration of mix being dependent on the amountof ingredients present in the chamber and the chamber can be of the typedisclosed in Application No. 8095/71 cognated with No. 55725/71. It hasbeen found preferable that the duration of mix should be of the order ofabout seconds. After mixing, the final mixture is transferred directlyby gravity into the core shooter or blowing chamber 6 by opening valves5 and 7. Valve 7 is then closed and the core shooter 6 is moved acrossto a posi tion as shown in FIG. 5 for the shooting operation. The coreor mould is shot by applying compressed air to the top and/or side ofthe core shooter and at the same time the mixing chamber 4 is purgedwith compressed gas into a suitable container. The core or mould isremoved and valve 5 is closed ready for the chamber 4 to receive furtheringredients for a fresh mix. The core shooter 6 is returned to itsoriginal position shown in FIG. 4 for the next cycle.

The core shooter or blowing head can be constructed to move on rollersrunning in tracks, slides or the like and driven by gears or pulleysfrom an electric motor. Alternatively, the driving force can be apneumatic or hydraulic piston and cylinder assembly and the core shooteror blowing head can be mounted for pivotal movement through a gearquadrant or the like.

It is envisaged that the arrangements shown in FIGS. 1, 2, .3 and 4 canoperate with mixing chamber constructions different to that describedabove and it is to be understood that the core shooters used with theequipment of the invention namely the supply means and movable mixingchamber, are in each case of a quite conventional known type.

I claim:

1. Apparatus for preparing foundry moulds or cores from coldquick-setting sand/binder/catalyst mixtures comprising a mixing chamber,supply means for providing the mixing chamber with separate charges ofsand and binder on the one hand and sand and catalyst on the other hand,a mechanical mixing element in the mixing chamber, an outlet from themixing chamber for passing material by gravity from the mixing chamberinto a blowing chamber, means for moving the mixing chamber and theblowing chamber apart to allow the final mixture to be discharged fromthe blowing chamber into a mould or core box and to allow the mixingchamber to be purged and purging means for the mixing chamber. 1

2. Apparatus according to claim 1 wherein the mixing chamber is movablebetween a first position in which it is adapted to deliver the mixedmaterial to the blowing chamber, and a second position in which themixing chamber is adapted to be purged by said purging means.

3. Apparatus according to claim 1 wherein the blow ing chamber ismovable between a first position in which it is adapted to receive thefinal mixture from the mixing chamber, and a second position in whichthe final mixture can be discharged into the mould or core box.

4. Apparatus according to claim 1 wherein said purging means comprisesmeans for supplying gas to the chamber.

5. Apparatus according to claim 1 wherein the mixing chamber comprises avertical cylindrical wall, a base wall with an outlet therein and avertical axis rotary mixing element in the chamber, the elementcomprising a pair of angle iron members tangentially mounted tosaid'axis and having rigid blades attached thereto adapted to sweep thebase wall and a pair of spring steel blades angularly offset from saidpair of angle iron members adapted to sweep the vertical wall.

6. Apparatus according to claim 5 wherein said second pair of blades arefixedly attached to a cross member which also serves to sweep a roof ofthe mixing chamber.

7. Apparatus according to claim 6 wherein the outlet of the mixingchamber is offset from an inlet of the mixing chamber through 270 in adirection of rotation of the rotary mixing element.

8. Apparatus according to claim 7 wherein the outlet of the mixingchamber is provided with a time controlled outlet valve adapted to closethe outlet during a mixing operation and to open the outlet after apredetermined time interval for discharging the final mixture into theblowing chamber.

9. Apparatus according to claim 8 wherein metered amounts of saidseparate charges are intermixed in the mixing chamber in separatebatches for a time interval of 10 seconds.

10. Apparatus according to claim 1 wherein the mixing chamber comprisesa vertical cylindrical wall, a base wall with an outlet therein and avertical axis rotary mixing element in the chamber, the outletcomprising a pair of angle iron members tangentially mounted to saidaxis and having rigid blades attached thereto adapted to sweep the basewall and a pair of 11. Apparatus according to claim 10 wherein thetotary mixing element is rotated at a speed of RPM.

12. Apparatus according to claim 1 wherein the mixing chamber comprisesa vertical cylindrical wall which is provided with tangentially disposedports for connec tion to a source of said cleaning means to purge anymaterial remaining in the mixing chamber, after discharge of the finalmixture, into a suitable receptacle. =k =l

1. Apparatus for preparing foundry moulds or cores from cold quick-setting sand/binder/catalyst mixtures comprising a mixing chamber, supply means for providing the mixing chamber with separate charges of sand and binder on the one hand and sand and catalyst on the other hand, a mechanical mixing element in the mixing chamber, an outlet from the mixing chamber for passing material by gravity from the mixing chamber into a blowing chamber, means for moving the mixing chamber and the blowing chamber apart to allow the final mixture to be discharged from the blowing chamber into a mould or core box and to allow the mixing chamber to be purged and purging means for the mixing chamber.
 2. Apparatus according to claim 1 wherein the mixing chamber is movable between a first position in which it is adapted to deliver the mixed material to the blowing chamber, and a second position in which the mixing chamber is adapted to be purged by said purging means.
 3. Apparatus according to claim 1 wherein the blowing chamber is movable between a first position in which it is adapted to receive the final mixture from the mixing chamber, and a second position in which the final mixture can be discharged into the mould or core box.
 4. Apparatus according to claim 1 wherein said purging means comprises means for supplying gas to the chamber.
 5. Apparatus according to claim 1 wherein the mixing chamber comprises a vertical cylindrical wall, a base wall with an outlet therein and a vertical axis rotary mixing element in the chamber, the element comprising a pair of angle iron members tangentially mounted to said axis and having rigid blades attached thereto adapted to sweep the base wall and a pair of spring steel blades angularly offset from said pair of angle iron members adapted to sweep the vertical wall.
 6. Apparatus according to claim 5 wherein said second pair of blades are fixedly attached to a cross member which also serves to sweep a roof of the mixing chamber.
 7. Apparatus according to claim 6 wherein the outlet of the mixing chamber is offset from an inlet of the mixing chamber through 270* in a direction of rotation of the rotary mixing element.
 8. Apparatus according to claim 7 wherein the outlet of the mixing chamber is provided with a time controlled outlet valve adapted to close the outlet during a mixing operation and to open the outlet after a predetermined time interval for discharging the final mixture into the blowing chamber.
 9. Apparatus according to claim 8 wherein metered amounts of said separate charges are intermixed in the mixing chamber in separate batches for a time interval of 10 seconds.
 10. Apparatus according to claim 1 wherein the mixing chamber comprises a vertical cylindrical wall, a base wall with an outlet therein and a vertical axis rotary mixing element in the chamber, the outlet comprising a pair of angle iron members tangentially mounted to said axis and having rigid blades attached thereto adapted to sweep the base wall and a pair of spring steel blades angularly offset from said pair of angle iron members adapted to sweep the vertical wall, the mixing chamber having an inlet, the outlet of the mixing chamber being offset from the inlet through 270* in a direction of rotation of the rotary mixing element and wherein the outlet of the mixing chamber is permanently open so that the material in the mixing chamber is intermixed by the rotary mixing element as said material is passed substantially straight through the mixing chamber and into the blowing chamber.
 11. Apparatus according to claim 10 wherein the rotary mixing element is rotated at a speed of 120 RPM.
 12. Apparatus according to claim 1 wherein the mixing chamber comprises a vertical cylindrical wall which is provided with tangentially disposed ports for connection to a source of said cleaning means to purge any material remaining in the mixing chamber, after discharge of the final mixture, into a suitable receptacle. 